Extension, osmotic tolerance and cryopreservation of saltwater crocodile (Crocodylus porosus) spermatozoa

• Published in: Aquaculture 2014-04, Vol.426-427, p.213-221
• Main Authors: Johnston, S.D., Lever, J., McLeod, R., Qualischefski, E., Brabazon, S., Walton, S., Collins, S.N.
• Format: Article
• Language: English
• Subjects: Aquaculture; Cold shock; Crocodiles; Crocodilian; Dimethylacetamide (DMA); Dimethylsuphoxide (DMSO); Glycerol; Plasma; Sperm preservation; Toxicity
• ISSN: 0044-8486; 1873-5622
• DOI: 10.1016/j.aquaculture.2014.02.014

Semen collected from 10 saltwater crocodiles (Crocodylus porosus) was used to investigate sperm in vitro manipulation and preservation. Preliminary studies revealed that phosphate buffered saline (PBS) without Ca2+, Mg2+ and egg yolk (EY) was a suitable extender for studies of sperm physiology. Spermatozoa diluted in PBS showed no change in survival [% motility (M), rate of sperm movement (R) and % plasma membrane integrity (PI)] when diluted over a range of 1:1 to 1:16. Except for a small decline in PI, there was no change in sperm survival when semen diluted without EY was cooled rapidly to and rewarmed from 0°C. The addition of EY (0, 5, 10 and 20% v/v) had no beneficial effect on sperm survival when incubated in PBS for 1h at 30°C or after 24h storage at 4°C. Whilst crocodile spermatozoa exposed to a range of anisotonic media and then returned to solutions of 390mosMkg−1 retained their M from 220 to 390mosMkg−1, PI remained high in hypotonic media (25–280mosMkg−1); spermatozoa showed an increase (P